Differences in rotifer communities in two freshwater bodies of different trophic degree (Lake Ohrid and Lake Dojran, Macedonia)

Abstract

We investigated monogonont rotifers in two natural Macedonian lakes that greatly differ in age, size and trophic state: Lake Ohrid and Lake Dojran. A main characteristic of Lake Ohrid is the scarcity of nutrients and consequently a low level of primary production. Lake Dojran represents a typical eutrophic lake. Results clearly indicate that species numbers are negatively correlated with trophic degree. Qualitative analyses of rotifer compositions in Lakes Ohrid and Dojran showed the presence of 70 and 55 taxa, respectively. Rotifer assemblages differed in their community structure, population densities, and the occurrence pattern of dominant species. (in September, 2005) were recorded in Lake Dojran. Gastropus stylifer and Keratella cochlearis were the most abundant species in the pelagic zone of Lake Ohrid, averaging monthly densities of 1.2 ind. L −1 and 0.6 ind. L −1 , respectively, thereby contributing 29% and 15% to rotifer abundance. In contrast, Lake Dojran rotifers were dominated by Brachionus spp. Brachionus diversicornis and Brachionus calyciflorus f. amphiceros were most abundant, comprising 40% and 25% of the total rotifer density. These results corroborate our idea, that the trophic state is an important factor in determining the composition of rotifer communities.

Zooplankton and environmental factors of a recovering eutrophic lake (Lysimachia Lake, Western Greece)

“…Generally, the diversity of a zooplankton community tends to decrease as a water body becomes more eutrophic, while the common characteristic of such ecosystems is the presence of a few dominant species with high density (Michaloudi & Kostecka 2004;Tasevska et al 2012). In Lake Lysimachia, however, the values and seasonal variation of the diversity index exhibited remarkable similarities with those recorded in the nearby oligotrophic Lake Trichonis (Doulka 2010) and the mesotrophic Lake Amvrakia (Chalkia et al 2012a).…”

“…Most of the rotifer species found in Lake Lysimachia are associated with high trophic state (Bērziňš & Pejler 1989). In more persistently eutrophic waters, certain species become numerically important constituents of the rotifer community, as in the cases of Lake Koroneia (Michaloudi & Kostecka 2004) and Lake Dojran (Tasevska et al 2012), where the rotifer community dominated by the eutrophic Brachionus species. In contrast, the high abundance of a relatively diverse group of eurytopic rotifer species in Lake Lysimachia suggests that the lake may be experiencing an intermediate than a highly enriched trophic state.…”

Diversity measures in macroinvertebrate and zooplankton communities related to the trophic status of subtropical reservoirs: Contradictory or complementary responses?

“…Numerous biological attributes of these communities can be used as indicators of the ecological quality of water bodies, such as: (i) abundance -used as a tool in the context of trophic status, relating the number of individuals observed to the fluctuation in environmental variables (Watson and Carpenter, 1974;Guijun et al, 2012;Tasevska et al, 2012); (ii) richness -an important attribute whose variation is associated with several factors intrinsic to the dynamics of the system. Researchers admit that richness can be used to prioritize areas for conservation, although it is an attribute that is influenced by the geographic region and sampling effort (Graça et al, 2004;Fleishman et al, 2006); (iii) taxonomic diversity -considers the presence and absence of species as a system evaluation criterion, and is often related to the observed pattern of abiotic variables (Arcifa, 1984;Patalas, 1971); and (iv) biomass -used in the development of metrics for environmental assessment, particularly in terms of system maintenance power (Salas et al, 2005;Peretyatko et al, 2009;Silow and In-Hye, 2004;Molozzi et al, 2013).…”

Complexity of diatom response to Lateglacial and Holocene climate and environmental change in ancient, deep and oligotrophic Lake Ohrid (Macedonia and Albania)

“…Lake Ohrid is alkaline, with pelagic water pH 8. 0-8.9 (measured in 2004-2006Tasevska et al, 2012) and ionic composition dominated by bicarbonate and calcium (Stanković, 1960). It is highly oligotrophic, with total phosphorus and total nitrogen concentration throughout the water column at the lake centre of 4.6-6.8 and 171-512 µg L −1 , respectively (measured in 2000-2001Watzin et al, 2002) and low dissolved silica concentration of < 0.2 mg L −1 in the trophogenic zone in summer (in 1957;Stanković, 1960).…”